Films formed from silicon nitride (Si.sub.3 N.sub.4) are becoming more widely used in conjunction with microelectronic devices such as wafers employed in integrated circuit devices. The silicon nitride may be used as an insulating film, a dielectric film, or a passivation film on the wafer. Silicon nitride is perceived to be desirable since it is capable of exhibiting good physical and chemical stability. There may be an increased demand for highly integrated circuits. These circuits may require reduced film thicknesses, improved film quality, increased dielectric levels, and increased mechanical strength. Additionally, it would be desirable if films used in the highly integrated circuits provide adequate vapor barrier and sodium barrier properties. The use of silicon nitride may be desirable for use in films which are capable of displaying these improved properties.
Utilization of silicon nitride, however, may present difficulties. Because silicon nitride often exhibits a high level of stabilization, it may be difficult to etch. In particular, it is often difficult to form a silicon nitride film at a temperature less than 450.degree. C. and then etch the film at a high resolution. Conventionally, a wafer comprising a silicon nitride film thereon is dipped into an etching chamber containing phosphoric acid (H.sub.3 PO.sub.4), and then the etching chamber is heated to a temperature ranging from 150.degree. C. to about 170.degree. C. to thereby etch the silicon nitride film. This etching process may be disadvantageous in that the etching rate is often slow, for example 50 .ANG./min. As a result, the production rate of integrated circuit devices using films etched by this process may be adversely affected. Moreover, the etching apparatus may become damaged as a result of the above procedure.
More recently, attempts have been made at etching silicon nitride films using an oxide film etch mask method or a plasma etching method in trying to obtain higher etch resolutions. The oxide film mask method attempts to improve the etching resolution by using hydrogen fluoride (HF) wet etching technology. Notwithstanding any potential advantages, the oxide film mask method is often complicated from a processing standpoint due to the use of a mask, and also because of the slow etching rate. A plasma etching method typically involves the ionization of etching gas, and the chemical or physical removal of the gas by the acceleration of the gas on the wafer surface. Equipment costs for carrying out this method, however, are typically high since largescale, complicated equipment is typically used. Moreover, a high level of power is usually required to carry out the plasma etching method.
There is a need in the art for etching compositions and methods of using the same which are more efficient than conventional methods in terms of equipment cost. There is also a need in the art for etching compositions and methods of using the same which can provide faster etching rates than realized using conventional etching solutions.